Relay



1942. K. w. PFLEGER RELAY Filed Oct. 5, 1940 R E V R E m5 M m W WW A Q 0Patented Dec. 1, 942

UNITED STATES PATENT OFFICE amass Kenneth w. Pfleger, Arlington, N. 5.,assignor to Bell Telephone Laboratories, Incorporated,

New York, N. Y., a' corporation of New York Application October 5,1940,Serial No. 359,882

5 Claims. (01. 1 5-320) This invention relates to high speed magneticrelays of the polar type. v

The armatures of such relays frequently bounce -upon striking theircontacts or pole-pieces. They may rebound more than once and such singleand V multiple rebounds are commonly known as chatter.

An object of the present invention is to reduce or eliminate chatter.

This object is achieved by means of electrical damping; an electricaldamping circuit magnetically coupled to the armature is tuned preferablyto the principal frequency at which the relay armature tends to chatter.

In one form the electrical damping means may consist of tuned circuitsincluding windings mounted upon and surrounding the pole-pieces of anotherwise conventional relay; in another form one or more of thewindings of the energizing coil which surrounds the armature may beincluded in the tuned circuit.

The nature and details of these improvements may be more convenientlyfurther described with reference to the accompanying drawings in which efigure is a top view of semi-diagrammatic nature of a standard type ofpolar telegraph relay having the improvements of the present inventionincorporated therein.

In its fundamental features of construction the specific relaydisclosedin the present application may be similar to that disclosed in thepatent to Cummings 1,624,476, granted April 12, 1927, or Curtis1,680,667, granted August 14, 1928; it may be considered as animprovement upon relays of the type disclosed in those patents.

The relay consists of an electromagnet comprising an energizing coil 8through which armature 9 extends. The coil 8 may and does in practiceconsist of one or up to several windings which may be connected todiiierent sources, such as line current sources, polarizing currentsources, etc., but is conventionally illustrated as being connected to asource of positive and negative battery over a line or other conductor,which may be of any length, to an armature III of an impulse originatingrelay which supplies impulses to vibrate the armature 8. The armature 9is clamped by means of a screw H or any other suitable means betweenmagnetic members of a permanent magnet structure I2. The armature =lvibrates between adjustable contacts 13 and is limited in motion bycontact members (not shown) on adjustable stop screws H which are ofmagnetic construction and terminate in pole-pieces ture flows into thearmature structure. The armature is generally clamped between non-manetic shims l6. So far as described the construction is conventional andknown.

A description will now be given of the novel features constituting theimprovements to which this specification is primarily directed. v Thepole-pieces i5 may be surrounded with a winding I! included in serieswith a capacity I! and a resistance IS. The capacity, resistance andwinding are connected in series and their values may be initiallyproportioned or they may be made adjustable so as to be tuned to theprincipal frequency of chatter and the resistance may be adjusted tointroduce the required dissipating efliect for oscillatory electricalenergy.

The natural period of vibration of the armature establishes theperiodicity or frequency at which the most troublesome chatter takesplace. This frequency may be estimated, for a relay of a particulardesign, from examination of oscillograms of the output current of therelay when low driving currents are used to operate it or it may beestimated from the shadow of the armature projected 'upon a rapidrecording oscillagraph film. Another method which could be used is toconnect an oscillator to one or more windings of the relay and vary thefrequency of the oscillator until maximum response of the armature isobserved, always using a driving current low enough to prevent completeoperation of the armature. During this process the armature shouldremain on one-contact except for possible chatter and a slight motionnear the pole-pieces may be observed. This observation may be made witha magnifying glass and the armature has the appearance of being thickestwhen the frequency corresponding to the natural period is reached. Thecircuit consisting of the elements l1, l8 and i 9 is then tuned or theelements predeterminedly I sponse which will be the point at which thedamping circuit produces the maximum damping effect. If desired, also,the line windings may be connected to the line and a direct current keptflowing in the line winding about equal to the highest value attained'by the line current upon a single impulse of telegraph frequency; thepurpose of II through which the flux to operate the armathis is to keeprelay winding in substantially the same condition that it is in when thedamping of the armature is useful.

An alternative form comprises connecting one of the windings of the coil8 in a series circuit including an adjustable condenser and aresistance. The coil 8 usually has several windings and one of theotherwise unused windings may be used for this purpose or the relay maybe specially constructed, if desired, with a spare winding. Thecondenser 20 and the resistance 2| may be proportioned and the dampingcircuit tuned in accordance with the same general principles asdiscussed in connection with the elements I1, II and 19. The switch 22may be employed to open the circuit consisting of the elements 20 and 2|at times and these elements may be employed either alternatively to theelements l1, I8 and N or all of them may be used together in the samerelay, Preferably, however, either set but not both may be employed.

The windings I i may be mounted upon the polepieces in the form ofinsulated spools the body of which may consist of any suitableinsulating material such as wood, hard rubber or a phenol condensationproduct. These spools may be slidably mounted upon the pole-pieces butfixed in place by any suitable means such as screws, adhesives, ori'rictionally during use.

What is claimed is:

1. A polar relay having means to reduce armature vibration and chatterconsisting of tuned circuits each having a winding about an operatingpole face of the relay and characterized in that the circuits are tunedto the natural frequency at which the armature tends to vibrate orchatter.

2. A polar relay having an armature subject to spurious vibration orchatter, one or more winding; or operating said armature, and a windingelectromagnetically related to said armature included in a circuit tunedto approximately the principal frequency at which said spuriousvibrations or chatter tend to occur.

3. A high speed polar relay comprising an armture, a permanent magnetstructure having opposing poles within which the armature is mounted,one or more operating windings (or said armature to which currents ofsuitable polarity and magnitude may be applied to move the armature ineither one of two opposing directions, and an anti-chatter windingsurrounding said armature, said winding being included in a tunablecircuit consisting of inductance and capacity with a variableresistance.

4. A polar relay having main operating winding means and means to reducearmature vibration and chatter consisting of tuned circuits eachincluded in a supplemental winding about an operating pole face of therelay and characterized in that the circuits are tuned to the naturalfrequency at which the armature tends to vibrate or chatter.

5. A polar relay having an armature subject to spurious vibration orchatter from mechanical causes independent of forces applied to itsoperating winding to operate the armature thereof, one or more windingsfor operating said armature, and a winding electromagnetically relatedto said armature included in a circuit tuned to approximately theprincipal frequency at which said spurious vibrations or chatter tend tooccur.

KENNETH W. PFLEGER.

